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Optimize ternaries with boolean consequent or alternative.

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Fixes #511
This commit is contained in:
kzc
2016-04-02 00:21:13 -04:00
committed by Richard van Velzen
parent 45ddb9caeb
commit 98434258d0
2 changed files with 109 additions and 19 deletions
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58
lib/compress.js
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@@ -2658,24 +2658,58 @@ merge(Compressor.prototype, {
}
}
// y?true:false --> !!y
if (is_true(consequent) && is_false(alternative)) {
if (self.condition.is_boolean()) {
// boolean_expression ? true : false --> boolean_expression
return self.condition;
if (is_true(self.consequent)) {
if (is_false(self.alternative)) {
// c ? true : false ---> !!c
return booleanize(self.condition);
}
self.condition = self.condition.negate(compressor);
return make_node(AST_UnaryPrefix, self.condition, {
operator: "!",
expression: self.condition
// c ? true : x ---> !!c || x
return make_node(AST_Binary, self, {
operator: "||",
left: booleanize(self.condition),
right: self.alternative
});
}
// y?false:true --> !y
if (is_false(consequent) && is_true(alternative)) {
return self.condition.negate(compressor)
if (is_false(self.consequent)) {
if (is_true(self.alternative)) {
// c ? false : true ---> !c
return booleanize(self.condition.negate(compressor));
}
// c ? false : x ---> !c && x
return make_node(AST_Binary, self, {
operator: "&&",
left: booleanize(self.condition.negate(compressor)),
right: self.alternative
});
}
if (is_true(self.alternative)) {
// c ? x : true ---> !c || x
return make_node(AST_Binary, self, {
operator: "||",
left: booleanize(self.condition.negate(compressor)),
right: self.consequent
});
}
if (is_false(self.alternative)) {
// c ? x : false ---> !!c && x
return make_node(AST_Binary, self, {
operator: "&&",
left: booleanize(self.condition),
right: self.consequent
});
}
return self;
function booleanize(node) {
if (node.is_boolean()) return node;
// !!expression
return make_node(AST_UnaryPrefix, node, {
operator: "!",
expression: node.negate(compressor)
});
}
// AST_True or !0
function is_true(node) {
return node instanceof AST_True